622 



INDEX 



Pondvveed, see Potamogeton 

 Pontederiaceae, 494 

 Poplar, see Popiilus 

 Poppy, see Papaver 



— oil, 265 



Populus (Aspen, Balsam Poplar, Cotton- 

 wood, Poplar), 68, 102, 246, 269, 

 281, 325, 340, 342-6, 365, 372, 375, 



376, 454, 544, 553 

 — , dominant, 343 



P. tremiiloides (American Aspen, 

 Trembling Aspen), 346, 553 

 Pore Fungus, 45 

 PoroUthon onkodes, 529 

 Porphvra capensis, 531 

 Porsild, A. E., 198 

 Posidonia, 317 



P. oceanica, 530 

 Post-Miocene flora, impoverishment of, 

 160 



Pleistocene flora, 165, 173-5 



immigration, 165 



Postclimax, 331, 361, 390, 393, 402 

 Postelsia, dwarfed, 526 



P. pahnaefoniiis, 525, 534 

 Postglacial changes, 165, 173-5, 201 



— climatic succession, 173-4, 201 



— peat, 1 5 1-2 



— relic, 197, 201 



Pot Geranium (Pelargonium), 275 



Potamogeton (Pondweed), 108, 112, 117, 

 319, 325, 500, 503, 504 

 P. natans, 504 



Potamogetonaceae, 494 



Potamoplankton, 479, 488, 489 



Potash, algal source of, 265 



Potato, see Solanum tuberosum 



— , grown in Far North, 231 



— , Late Blight of, see Phytoplithora 

 • infest ans 



Potential area, 176, 209, 215, 224 



Potentilla egedii agg. (Pacific Silver- 

 weed), 399, 400 

 P. saundersiana ^'ar. caespitosa, 412 



Poterium sanguisorba (Salad Burnet), 79 



Poverty-grass, see Danthonia 



Prairie, 85, 343, 360, 361, 362, 363 



— , mid-grass, 361, 362 



— , overgrazed, 361, 362 



— , short-grass, 361, 362 



— soil, 298, 299 

 Prantl, K., 74 

 Prasiola, 524 

 Pre-Boreal period, 173, 174 



Cambrian era, 128, 129, 130, 145, 



146 



■ , Algae of, 129, 130, 146 



, Bacteria of, 146 



Pleistocene southward migration, 



161 

 Tertiary relics, 201 



Precipitation (rainfall, snow, hail, dew), 

 10, II, 288-9, 290, 294, 338, 345, 

 349, 350, 354, 350, 366, 376, 424, 

 439, 442, 444, 467, 474, 555. 574 



— , annual, 288-9, 290, 381, 441 



— , arctic, 316, 381 



— in arid regions, 364-6, 447-52 

 — , world map of, 290 



— , chemical, 495, 497 

 Preclimax, 331, 361, 390 

 Predation, plankton and, 488, 519 

 Prescott, G. W., xviii, 483, 487, 491 

 Prevailing climax, 330 

 Prevernal aspect, 285, 340, 342 

 Prickly Lettuce, see Lactuca scariola 



pear, see Opuntia 



Primary climatic grouping, 10, 11 



— producers, Algae as, 278-9, 515 



— sere, 324 



— xerosere, 325-8, 464 



Primitive Angiosperms, suggestions of, 



139, 144 



— organisms, 129-30 

 Primofilices, 138 



Prince Charles Island, 127 



— Edward Island, 420 



— of Wales Island, 397, 398 

 Principles of cultivation, 310-11 

 Prinalea antiscorbutica (Kerguelen Cab- 

 bage), 417, 419, 420 



Prisere, 324 



Producer plants, 257, 480 

 Productive capacity, 509, 541 

 Productivity of land and sea compared, 

 520 



— types, fresh waters, 318, 319, 476-8 

 Profile diagram, 425, 426 



— , lake-marginal, 493 

 — , sea-marginal, 513 

 — , soil, see Soil profile 

 Profundal region, 493, 496, 498, 503 

 Progression to climax, 324 

 Progressive changes in dominants, 464 

 Prop-roots, 455, 456, 458, 459 

 Proseral benthos, 503 



— Lichens, 327 



■ — planktonic etc. deposition, 325 

 502-3 



— Schizophytes, 326 



Protea, 2S5 



Protective coloration in animals, 424 



— covering, loss in culti\ation, 217 

 Proterozoic era, 128, 130, 131, 145 

 Prothallus, 56, 57, 59, 63 

 Protolepidodendrales, 145 

 Protolepidodendron primaevum, 147 

 Protonema {pi. protonemata), 52, 53, 



491 

 Protoplasm, 13, 321, 508 

 Protozoa, 305, 495 

 Prune, 258 



